394 Trans. Acad. Sci. of St. Louis 
of the pupa was the same as in the last, with the addition 
of the pigmentation of the eyes, at that time a light 
brown color. This continuous series of changes, it will 
be noticed, is directly opposite to the order of the de- 
position of the eggs. This succession of development 
had brought them to maturity so that the last egg de- 
posited was ready to be first to emerge as an adult, and 
the oldest egg was to leave the nest last! A wonderful 
adaptation for safeguarding the young at the critical 
time of birth! But how did it come about, and if an adap- 
tation, why do not all the relatives follow the same ad- 
vantageous principle? ‘All of these wasps pupated with 
the head up, as usual. This order of development, the 
oldest in the bottom in the earliest stage and ranging to 
the youngest on top in the most advanced stage, con- 
tinued unvaryingly through every stage of their develop- 
ment to adulthood and the point of emergence. Then, 
for reasons which I could not understand, the two upper- 
most died in their cells. The three lower ones broke 
through their own roofs, but, owing to the failure of 
their brothers above them to provide for them an exit 
from this point on, they all perished, imprisoned in the 
large middle cell. This is certainly bringing adapta- 
tion to a point of refinement beyond utility. It would 
be highly interesting to know whether those lower ones 
died in the middle cell after having escaped from their 
own because they did not have strength to break through 
the other parts above, or whether they simply did not 
have the wit to try. But whatever the cause, we are 
quite sure that they would leave no offspring to perpetu- 
ate their physical weakness or intellectual lethargy. 
One dipterous parasite which emerged from one of 
these nests was identified as Toxophora amphitea Walk. 
[C. T. Greene]. 
